Terra Theraic and Magnesium Oxide with Induced Defects as Additives on Concrete for the Protection of Rebars

Normalized concrete specimens, blank and with 4% Terra Theraic (natural material of volcanic origin) or 4% magnesium oxide (MgO) with induced defects (SIMAC) were placed in renewed seawater, and the weight loss measurements of the rebars were taken. The same measurements were taken on the same type of specimens under cathodic protection (−850 mV), protected with our method of needle-diodes or under anodic charge (+850 mV). Some measurements were also taken for specimens immersed directly in the sea by the aid of an experimental raft. Protective properties are presented in a table, and it follows from these findings that the two Greek additives are adequate for a good protection of the rebars. The corrosion in the ocean for a short immersion period is lower than in the laboratory (same seawater) because in the laboratory we have no fouling on the specimens, which in the ocean retards the corrosion by the formation of a biological membrane.